High molecular weight hydrocarbon soluble polymers, such as polyisobutylene, polystyrene and several alpha olefins, have been demonstrated to reduce drag in turbulent flows of hydrocarbon liquids. Generally, the drag reduction effectiveness of these polymers improves with increasing molecular weight; however, the tendency for the polymers to permanently degrade via molecular scission in local extensional flows within pumps or turbulent pipeflows also increases with increasing polymer molecular weight. This invention discloses efficient drag reduction in organic liquids resulting from a novel class of interpolymer complexes containing sulfonated copolymers of alpha olefins.
It is well known that alpha olefins can be polymerized in the presence of coordination catalysts (Ziegler-Natta). These catalysts generally consist of materials such as transition metal halides (e.g., TiCl.sub.3) and organometallic cocatalysts (e.g., R.sub.3 Al or R.sub.2 AlCl). Most of the efforts in this field have centered on maximizing catalyst activity and polymer stereoregularity/crystallinity (e.g., U.S. Pat. Nos. 3,116,274, 3,476,730, 3,156,681 and 4,240,982). Items of commerce in this category are isotactic polypropylene and poly(1-butene). These stereoregular, crystalline polymers have excellent physical and mechanical properties and are well suited to forming molded objects, such as pipe or tubing, which require rigidity. However, these materials have limited use as polymer additives to hydrocarbon solutions (e.g., viscosifiers, drag reducers, antimisting agents).
A smaller body of knowledge exists on the preparation of ultra-high molecular weight noncrystalline alpha olefins suitable for use as hydrocarbon viscosifiers, drag reducing agents or antimisting additives, etc. Examples of such art are found in U.S. Pat. Nos. 4,289,679, 4,358,572, 4,371,455 and British Pat. No. GR 2074,175A. The noncrystalline nature of these polymers makes them amenable to easy dissolution in organic media. However, these materials are completely nonfunctional and their solution properties can be optimized only by adjustment of polymer molecular weight (+ distribution). In other words, there are no reactive groups on these chains suitable for modification or interaction.
Reports of functional alpha olefins in Ziegler-Natta polymerizations are sparse. A notable exception is the copolymerization of propylene with the methyl ester of undecanoic acid (Japanese Patent Application Nos. 57-152767, 57-188996, 57-188997). However, the product of this reaction is characterized by very low levels (0.1-0.3 mole percent) of functional group incorporation. Also, this polymer product is highly crystalline and, thus, not useful as hydrocarbon viscosifiers, drag reducing agents or antimisting additives.
The instant invention is distinguished from the functional/short chain alpha olefin art (Japanese Patent Application Nos. 57-152767, 57-188996, 57-188997) by the lower levels of crystallinity. Thus, the instant composition is useful for hydrocarbon solution applications, e.g., drag reduction, viscosification, antimisting additives, etc., whereas the crystalline polymers of prior art are not. In the instant invention functionalization of a copolymer of octene-1 is achieved by sulfonation, which in turn enables association of shorter molecular weight chains into a larger system effective for drag reduction. The sulfonation requires a copolymerization with a monomer resulting in a double bond in or pendent to the polymeric chain.
In U.S. Pat. No. 4,508,128 complexes of Zn-S-EPDM/styrene vinylpyridine are described. The complexes of the instant invention are more soluble in organic liquids, such as crude oil, than those described in U.S. Pat. No. 4,508,128 as a result of the inherently lower levels of crystallinity obtained with 1-octene rather than ethylene/propylene (EP) polymers. This enhanced solubility is most pronounced for very high molecular weight (&gt;1,000,000) polymers and generally improves polymer drag reduction activity.
The present invention discloses drag reduction agents for organic liquids which are polymer complexes of a copolymer of polystyrene vinylpyridine complexed with a zinc salt of a sulfonated 1-octene/ethylene/ethylidene norborene terpolymer.